1. Field of Invention
The present invention relates to a check processing system for sending and managing image information and magnetic ink character information that is captured from a check by a check processing terminal and sent to a host device to which the check processing terminal is connected. The invention relates more particularly to a check information tampering detection method that can determine if the image information or magnetic ink character information read from a check has been tampered with on the host device.
2. Description of Related Art
Checks that are used by customers at the point of sale to pay for a purchase are processed by a check processing terminal that reads the magnetic ink character information that is printed using magnetic ink on the front of the check and captures an image of the check front. An electronic funds transfer is then effected based on the account number and other bank information that is captured from the read magnetic ink character information. Once the electronic funds transfer is completed, delivering the physical check to the bank or other financial institution is not necessary, and the check is returned to the customer after the necessary information has been written on the check front and the check has been endorsed. Because the store will have no proof of the check payment once the check is returned to the customer, the scanned check image is stored as proof of payment.
The check processing terminal is usually located at the checkout counter and connected to the host computer (host device) by a cable. The host computer is typically connected to a server (host) over a communication line, the magnetic ink character information and image information captured by the check processing terminal is sent through the host computer to the server, and the server centrally manages check information from the check processing terminals. Japanese Unexamined Patent Appl. Pub. JP-A-2004-206362 teaches a check processing terminal that can be used in this type of check processing system.
When a fraudulent transaction occurs at a store, one possibility is that the image information or magnetic ink character information acquired by the check processing terminal has been tampered with before the information is sent to the server in order to change the face amount, for example. One possible solution to this problem is to embed information for detecting tampering with the transmitted image information as a digital watermark when the image information is sent from the host computer to the server, and have the server that receives the image information determine if the image information has been tampered with. Japanese Unexamined Patent Appl. Pub. JP-A-2001-78013 teaches a method that uses a digital watermark to determine if there has been any tampering with the image information.
However, software for tampering with the image information before the digital watermark is embedded could be installed to the host computer. In this case the server cannot detect tampering based on the received image information having the embedded digital watermark, and therefore cannot detect fraudulent transactions that occurred at the store.